Four port hybrid

ABSTRACT

The present invention relates to a four port hybrid comprising a first set ( 10 ) of N coupled transmission lines ( 10 A,  10 B,  10 C,  10 D,  10 E,  10 F,  10 G,  10 H,  10 I) and a second set ( 20 ) of N coupled transmission lines ( 20 A,  20 B,  20 C,  20 D,  20 E,  20 F,  20 G,  20 H,  20 I) where N≧4. Said coupled transmission lines in said first set ( 10 ) are electrically connected to said coupled transmission lines in said second set ( 20 ) to form a first spiral shaped electrical conductive path, a second spiral shaped electrical conductive path and N−1 electrically isolated transposition portions ( 30, 40, 50, 60, 70, 80, 90, 110 ) of said first and second spiral shaped electrical conductive paths. A first end of the first spiral being an input port (P 1 ). A first end of the second spiral being a port (P 4 ) connectable to ground. A second end of the first spiral being a first output port (P 3 ) and a second end of the second spiral being a second output port (P 2 ).

This is a nationalization of PCT/SE00/01621 filed Aug. 23, 2000 andpublished in English.

FIELD OF THE INVENTION

The present invention relates to microwave radio frequency transmissionline circuits generally and more specifically to four port hybrids.

DESCRIPTION OF THE RELATED ART

The requirement to integrate as much as possible in even smaller volumescalls for the study and development of new types of hybrids.

Hybrids are per se well known and well understood in this art in itswaveguide, coaxial, microstrip and stripline forms. Typical prior arthybrids are branch directional coupler, Lange coupler and tandemcoupler. These hybrids are fundamentally four port devices that accept asignal at an input port, divide the signal in half internally and thensupply the divided signal to two output ports. In an ideal quadraturehybrid, the difference in phase angle between the output ports remainsat 90 degrees and the amplitude of the output signals remain equalacross the useful bandwidth of the device. There is essentially nooutput from the fourth port as it is isolated from the input port, andin many instances said port is terminated internally. Once the inputport is selected the others are defined automatically.

The most common hybrid structure is a branch directional coupler. Theproblem with said hybrid is too large to be of any interest at afrequency band used in mobile telephones, e.g. a GSM or a PCS frequencyband.

Another hybrid is the one based on coupled lines arranged on one side ofa dielectric substrate. The problem with said hybrid is that it cannotbe realised using standard PCB technology due to too narrow gap between.

Yet another hybrid is the one based on coupled lines arranged onopposite sides of a dielectric substrate. The problem with said hybridis that the physical dimensions are too large and the necessity to useboth sides of said substrate with the added problem of double sidedalignment.

A further hybrid is the so called Lange coupler. The problem with saidhybrid is that the required 3 dB coupling between the transmission lineshas to be done with narrow transmission lines which are too narrow to becross connected by commercially available PCB (Printed CircuitBoard)-jumpers. Another problem with the lange coupler is that thephysical dimension is too large to be of any interest in applicationsdemanding small is space.

Still another hybrid is the so called tandem coupler. The problem withsaid hybrid is that the physical dimension is too large.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a four port hybridwhich overcomes or at least reduces the above mentioned problems.

Another object of the present invention is to provide a hybrid withcomparably small physical dimensions and improved electrical parameters.

According to the present invention there is provided a four port hybridas claimed in claim 1.

One advantage with the present invention is that the hybrid can bemanufactured in stripline or microstrip with comparably wide strips andcomparably wide gaps between said strips that results in a high Q-factorof the transmission lines which in turn leads to small insertion loss.

Another advantage with the present invention is that the hybrid is lesssensitive to fabrication tolerances and by that is inexpensive tomanufacture.

Yet another advantage is that the present invention being small enoughto make an implementation in MMIC (Monolithic Microwave Integratedcircuit) technology possible.

Still another advantage is that the present invention has improved bothreflection and insertion loss compared to already existing hybrids.

The invention will now be described in more detail with reference topreferred embodiments thereof and also with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of a first embodiment of a four porthybrid according to the present invention.

FIG. 2 shows a schematic view of a second embodiment of a four porthybrid according to the present invention.

FIG. 3 shows a schematic view of a third embodiment of a four porthybrid according to the present invention.

FIG. 4 shows a schematic view of a fourth embodiment of a four porthybrid according to the present invention.

FIG. 5 shows a first physical layout of a four port hybrid according tothe first embodiment of the present invention.

FIG. 6 shows a schematic view of a fifth embodiment of a four porthybrid according to the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENTS

With reference to FIG. 1, a schematic view of a first embodiment of afour port hybrid 100A according to the invention is shown. The hybrid100A comprising a first set 10 and a second set 20 of multiple coupledtransmission lines. Said first set of multiple coupled transmissionlines 10 comprising a first transmission line 10A, a second transmissionline 10B, a third transmission line 10C and a fourth transmission line10D. Said second set of multiple coupled transmission lines 20comprising a first transmission line 20A, a second transmission line20B, a third transmission line 20C and a fourth transmission line 20D.In the present embodiment the transmission lines 10A, 10B, 10C, 10D,20A, 20B, 20C, 20D are C-shaped. The first transmission line 10A, 20A isthe longest one and the second 10B, 20B, third 10C, 20C and fourth 10D,20D are decreasing by gradual stages. All transmission lines 10A, 10B,10C, 10D in the first set 10 are mutually coupled and said couplingbetween said transmission lines is of electromagnetic nature. The sameapplies to the second set of multiple coupled transmission lines 20. Afirst end of the first transmission line 10A in the first set of coupledtransmission lines 10 being an input port P1. A second end of saidtransmission line 10A is electrically connected to a second end of thesecond transmission line in the second set of coupled transmission linesvia an electrical conductor 32. A first end of the second transmissionline 20B in the second set of coupled transmission lines 20 iselectrically connected to a first end of the third transmission line 10Cin the first set of coupled transmission lines 10 via an electricalconductor 52. A second end of the third transmission line in the firstset of coupled transmission lines is electrically connected to a fourthtransmission line 20D in the second set of multiple coupled transmissionlines 20 via an electrical conductor 42. A first end of the fourthtransmission line in the second set of coupled transmission lines beinga first output port P3. The first transmission line 10A in the first set10, the second transmission line 20B in the second set 20, is the thirdtransmission line 10C in the first set 10 and the fourth transmissionline 20D in the second set 20 coupled electrically to each other viasaid electrical conductors 32, 42, 52 are forming a first spiral shapedelectrical conductive path.

A first end of the first transmission line 20A in the second set ofcoupled lines 20 being a terminated (isolated) port. A second end of thefirst transmission line 20A in the second set of coupled transmissionlines 20 is electrically connected to a second end of the secondtransmission line 10B in the first set of coupled transmission lines 10via an electrical conductor 34. A first end of the second transmissionline 10B in the first set of multiple coupled transmission lines 10 iselectrically connected to a first end of a third transmission line 20Cin the second set of coupled transmission lines 20 via an electricalconductor 54. A second end of the third transmission line 20C in thesecond set of coupled transmission lines 20 is electrically connected toa second end of a fourth transmission line 10D in the first set ofcoupled transmission lines via an electrical conductor 44. A first endof the fourth transmission line 10D in the first set of coupled linesbeing a second output port P2. The first transmission line 20A in thesecond set 20, the second transmission line 10B in the first set 10, thethird transmission line 20C in the second set 20 and the fourthtransmission line 10D in the first set of multiple coupled transmissionlines 20 are coupled electrically to each other via said electricalconductors 34, 44, 54 are forming a second spiral shaped electricalconductive path.

In the spiral shaped electrical conductive paths every second half turnof said spiral are belonging to the first set of coupled transmissionlines and between said half turns the transmission lines belonging tothe second set of transmission lines are arranged.

In the embodiment shown in FIG. 1 there are three electrically isolatedtransposition portions 30, 40, 50 of the first and second spiral shapedconductive paths. Said electrically isolated transposition portions canbe looked upon as four port lumped cross connectors. In a firsttransposition portion 30 the electrical conductors 32, 34 connecting thesecond end of the first transmission line 10A in the first set ofcoupled lines 10 to the second end of the second transmission line 20Bin the second set of coupled lines 20 and the second end of the secondtransmission line 10B in the first set of coupled transmission lines 10to the second end of the first transmission line 20A in the second setof coupled transmission lines 20 respectively. In a second transpositionportion 40 the electrical conductors 42, 44 connecting the second end ofthe third transmission line 10C in the first set of coupled lines 10 tothe second end of the fourth transmission line 20D in the second set ofcoupled lines 20 and the second end of the fourth transmission line 10Din the first set of coupled transmission lines 10 to the second end ofthe third transmission line 20C in the second set of coupledtransmission lines 20 respectively. In a third transposition portion 50the electrical conductors 52, 54 connecting the first end of the secondtransmission line 10B in the first set of coupled lines 10 to the firstend of the third transmission line 20C in the second set of coupledlines 20 and the first end of the third transmission line 10C in thefirst set of coupled transmission lines 10 to the first end of thesecond transmission line 20B in the second set of coupled transmissionlines 20 respectively.

With reference to FIG. 2, another embodiment of a four pore hybrid 100Baccording to the invention is shown. The structure of the hybrid 100B isthe same as the one shown in FIG. 1 except for the only difference offurther comprising six capacitors 31, 33, 41, 43, 51, 53. A firstcapacitor 31 is coupled between the second end of the first transmissionline 10A in the first set of coupled lines 10 and the second end of thefirst transmission line 20A in the second set of coupled transmissionlines. A second capacitor 32 is coupled between the second end of thesecond transmission line 10B in the first set of coupled lines 10 andthe second end of the second transmission line 20B in the second set ofcoupled transmission lines 20. A third capacitor 41 is coupled betweenthe second end of the third transmission line 10C in the first set ofcoupled lines 10 and the second end of the third transmission line 20Cin the second set of multiple coupled transmission lines 20. A fourthcapacitor 43 is coupled between the second end of the fourthtransmission line 10D in , the first set of coupled lines 10 and thesecond end of the fourth transmission line 20D in the second set ofcoupled transmission lines 20. A fifth capacitor 51 is coupled betweenthe first end of the third transmission line 10C in the first set ofcoupled lines 10 and the first end of the third transmission line 20C inthe second set of coupled transmission lines 20. A sixth capacitor 53 iscoupled between the first end of the second transmission line 10B in thefirst set of coupled lines 10 and the first end of the secondtransmission line 20B in the second set of coupled transmission lines20. Said capacitors are forming further RF connections between thetransmission lines in the first and second set of coupled transmissionlines. Said capacitors will improve directivity of the hybrid byequalizing phase velocities of different modes propagating in thehybrid.

With reference to FIG. 3, yet another embodiment of a four port hybrid100C according to the invention is shown. The hybrid 100C comprising afirst set 10 and a second set 20 of coupled transmission lines. Saidfirst set of coupled transmission lines 10 comprising a firsttransmission line 10A, a second transmission line 10B, a thirdtransmission line 10C, a fourth transmission line 10D, a fifthtransmission line 10E, a sixth transmission line 10F, a seventhtransmission line 10G, a eighth transmission line 10H and a ninthtransmission line 101. Said second set of transmission lines 20comprising a first transmission line 20A, a second transmission line20B, a third transmission line 20C, a fourth transmission line 20D, afifth transmission line 20E, a sixth transmission line 20F, a seventhtransmission line 20G, a eighth transmission line 20H and a ninthtransmission line 20I. In the present embodiment the transmission lines10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I, 20A, 20B, 20C, 20D, 20E,20F, 20G, 20H, 20I are C-shaped. The first transmission lines 10A, 20Aare the longest ones and the second 10B and 20B, third 10C and 20C,fourth 10D and 20D, fifth 10E and 20E, sixth 10F and 20P, seventh 10Gand 20G, the eighth 10H and 20H and the ninth 101 and 20I are decreasingby gradual stages. All transmission lines 10A, 10B, 10C, 10D, 10E, 10F,10G, 10H 10I in the first set 10 are mutually coupled and said couplingbetween the transmission lines is of electromagnetic nature. The sameapplies to the transmission lines in the second set of coupledtransmission lines 20. A first end of the first transmission line 10A inthe first set of coupled transmission lines 10 being an input port P1. Asecond end of said transmission line 10A is electrically connected to asecond side of the second transmission line 20B in the second set ofcoupled transmission lines 20 via an electrical conductor 32. A firstside of the second transmission line 20B in the second set of coupledtransmission lines 20 is electrically connected to a first side of thethird transmission line 10C in the first set of coupled transmissionlines 10 via an electrical conductor 112. A second end of the thirdtransmission line 10C in the first set of coupled transmission lines iselectrically connected to a second end of the fourth transmission line20D in the second set of coupled transmission lines via an electricalconductor 42. A first end of the fourth transmission line 20D in thesecond set of coupled transmission lines 20 is electrically connected toa first side of the fifth transmission line 10B in the first set ofcoupled transmission lines 10 via an electrical conductor 92. A secondend of the fifth transmission line 10E in the first set of coupledtransmission lines 10 is electrically connected to a second end of thesixth transmission line 20F in the second set of coupled transmissionlines via an electrical conductor 52. A first side of the sixthtransmission line 20F in the second set of coupled transmission lines 20is electrically connected to a first side of the seventh transmissionline 10G in the first set of coupled transmission lines 10 via anelectrical conductor 82. A second end of the seventh transmission line10F in the first set of coupled transmission lines 10 is electricallyconnected to a second end of the eighth transmission line 20H in thesecond set of coupled transmission lines via an electrical conductor 62.A first side of the eighth transmission line 20H in the second set ofcoupled transmission lines 20 is electrically connected to a first sideof the ninth transmission line 100 in the first set of coupledtransmission lines 10 via an electrical conductor 72.

The first transmission line 10A in the first set 10, the secondtransmission line 20B in the second set 20, the third transmission line10C in the first set 10 and the fourth transmission line 20D in thesecond set 20 The fifth transmission line 10E in the first set 10, thesixth transmission line 20F in the second set 20, the seventhtransmission line 10G in the first set 10 and the eighth transmissionline 20H in the second set 20 and the ninth transmission line in thefirst set are coupled electrically to each other via said electricalconductors 32, 112, 42, 92, 52, 82, 62, 72 are forming a first spiralshaped electrical conductive path.

A first end of the first transmission line 20A in the second set ofcoupled lines 20 being a terminated (isolated) port. Said termination isusually made with a system impedance which commonly is 50Ω. A second endof the first transmission line 20A in the second set of coupledtransmission lines 20 is electrically connected to a second end of thesecond transmission line 10B in the first set of coupled transmissionlines 10 via an electrical conductor 34. A first end of the secondtransmission line 10B in the first set of coupled transmission lines 10is electrically connected to a first end of a third transmission line20C in the second set of coupled transmission lines 20 via an electricalconductor 114. A second end of the third transmission line 20C in thesecond set of coupled transmission lines 20 is electrically connected toa second end of a fourth transmission line 10D in the first set ofcoupled transmission lines via an electrical conductor 44. A first endof the fourth transmission line 20D in the first set of coupledtransmission lines 10 is electrically connected to a first side of thefifth transmission line 10E in the second set of coupled transmissionlines 10 via an electrical conductor 94. A second end of the fifthtransmission line 20E in the second set of coupled transmission lines 20is electrically connected to a second end of the sixth transmission line10F in the first set of coupled transmission lines via an electricalconductor 54. A first end of the sixth transmission line 10F in thefirst set of coupled transmission lines 10 is electrically connected toa first side of the seventh transmission line 20G in the second set ofcoupled transmission lines 20 via an electrical conductor 84. A secondend of the seventh transmission line 20F in the second set of coupledtransmission lines 20 is electrically connected to a second end of theeighth transmission line 10H in the first set of coupled transmissionlines via an electrical conductor 64. A first side of the eighthtransmission line 10H in the first set of coupled transmission lines 10is electrically connected to a first side of the ninth transmission line20I in the second set of coupled transmission lines 20 via an electricalconductor 74.

A second end of the ninth transmission line 20I in the second set ofcoupled lines being a second output port P3.

The first transmission line 20A in the second set 20, the secondtransmission line 10B in the first set 10, the third transmission line20C in the second set 20 and the fourth transmission line 10D in thefirst set 10, the fifth transmission line 20E in the second set 20, thesixth transmission line 10F in the first set 10, the seventhtransmission line 20G in the second set 20, the eighth transmission line10H in the first set 10 and the ninth transmission line 201 in thesecond set 20 are coupled electrically to each other via said electricalconductors 34, 114, 44, 94, 54, 84, 64, 74 and forming a second spiralshaped electrical conductive path.

In the spiral shaped electrical conductive paths every second half turnof said spiral are belonging to the first set of coupled transmissionlines and between said half turns the transmission lines belonging tothe second set of transmission lines are arranged.

In the embodiment shown in FIG. 3 there are eight electrically isolatedtransposition portions 30, 40, 50, 60, 70, 80, 90, 110 of the first andsecond spiral shaped electrical conductive paths. Said electricallyisolated transposition portions can be looked upon as four port crossconnectors. In a first transposition portion 30 the electricalconductors 32, 34 connecting the second end of the first transmissionline 10A in the first set of coupled lines 10 to the second end of thesecond transmission line 20B in the second set of coupled lines 20 andthe second end of the second transmission line 10B in the first set ofcoupled transmission lines 10 to the second end of the firsttransmission line 20A in the second set of coupled transmission lines 20respectively.

In a second transposition portion 40 the electrical conductors 42, 44connecting the second end of the third transmission line 10C in thefirst set of coupled lines 10 to the second end of the fourthtransmission line 20D in the second set of coupled lines 20 and thesecond end of the fourth transmission line 10D in the first set ofcoupled transmission lines 10 to the second end of the thirdtransmission line 20C in the second set of coupled transmission lines 20respectively. In a third transposition portion 50 the electricalconductors 52, 54 connecting the second end of the fifth transmission isline 10E in the first set of coupled lines 10 to the second end of thesixth transmission line 20F in the second set of coupled lines 20 andthe second end of the sixth transmission line 10F in the first set ofcoupled transmission lines 10 to the second end of the fifthtransmission line 20E in the second set of coupled transmission lines 20respectively. In a fourth transposition portion 60 the electricalconductors 62, 64 connecting the second end of the seventh transmissionline 10G in the first set of coupled lines 10 to the second end of theeight transmission line 20H in the second set of coupled lines 20 andthe second end of the eight transmission line 10H in the first set ofcoupled transmission lines 10 to the second end of the seventhtransmission line 20G in the second set of coupled transmission lines 20respectively. In a fifth transposition portion 70 the electricalconductors 72, 74 connecting the first end of the ninth transmissionline 10I in the first set of coupled lines 10 to the first end of theeight transmission line 20H in the second set of coupled lines 20 andthe first end of the eight transmission line 10H in the first set ofcoupled transmission lines 10 to the first end of the ninth transmissionline 201 in the second set of coupled transmission lines 20respectively.

In a sixth transposition portion 80 the electrical conductors 62, 84connecting the second end of the seventh transmission line 10G in thefirst set of coupled lines 10 to the second end of the sixthtransmission line 20F in the second set of coupled lines 20 and thesecond end of the sixth transmission line 10F in the first set ofcoupled transmission lines 10 to the second end of the seventhtransmission line 20G in the second set of coupled transmission lines 20respectively. In a seventh transposition portion 90 the electricalconductors 92, 94 connecting the first end of the fifth transmissionline 10E in the first set of coupled lines 10 to the first end of thefourth transmission line 20D in the second set of coupled lines 20 andthe first end of the fourth transmission line 10D in the first set ofcoupled transmission lines 10 to the first end of the fifth transmissionline 20E in the second set of coupled transmission lines 20respectively.

In a eighth transposition portion 110 the electrical conductors 112, 114connecting the first end of the third transmission line 10C in the firstset of coupled lines 10 to the first end of the second transmission line20B in the second set of coupled lines 20 and the first end of thesecond transmission line 10B in the first set of coupled transmissionlines 10 to the first end of the third transmission line 20C in thesecond set of coupled transmission lines 20 respectively.

With reference to FIG. 4, a schematic view of a fourth embodiment of afour port hybrid 100D according to the invention is shown. The hybrid100D comprising a first set 10 and a second set 20 of coupledtransmission lines. Said first set of coupled transmission lines 10comprising a first transmission line 10A, a second transmission line10B, a third transmission line 10C and a fourth transmission line 10D.Said second set of transmission lines 20 comprising a first transmissionline 20A, a second transmission line 20B, a third transmission line 20Cand a fourth transmission line 20D. In the present embodiment thetransmission lines 10A, 10B, 10C, 10D, 20A, 20B, 20C, 20D are C-shaped.The first transmission lines 10A, 20A and the second transmission line10B, 20B are the longest ones and the third transmission lines 10C, 20Cand fourth transmission lines 10D, 20D are the shortest ones. Alltransmission lines 10A, 10B, 10C, 10D in the first set 10 are mutuallycoupled and said coupling is of electromagnetic nature. The same appliesto every transmission line in the second set of coupled transmissionlines 20 A first end of the first transmission line 10A in the first setof coupled transmission lines 10 being an input port P1. A second end ofsaid transmission line 10A is electrically connected to a second side ofthe second transmission line 20B in the second set of coupledtransmission lines via an electrical conductor 32. A first side of thesecond transmission line 20B in the second set of coupled transmissionlines 20 is electrically connected to a first side of the thirdtransmission line 10C in the first set of coupled transmission lines 10via an electrical conductor 52. A second side of the third transmissionline 10C in the first set of coupled transmission lines 10 iselectrically connected to a fourth transmission line 20D in the secondset of coupled transmission lines 20 via an electrical conductor 42. Afirst side of the fourth transmission line in the second set of coupledtransmission lines being a first output port P3. The first transmissionline 10A in the first set 10, the second transmission line 202 in thesecond set 20, the third transmission line 10C in the first set 10 andthe fourth transmission line 20D in the second set 20 coupledelectrically to each other via said electrical conductors 32, 42, 52 areforming a first spiral shaped electrical conductive path The first andthird transmission lines 10A and 10C belonging to the first set ofcoupled transmission lines are arranged on a first side of a dielectricsubstrate and the second and third transmission lines 20B and 20Cbelonging to the second set of transmission lines are arranged on asecond side of said dielectric substrate.

A first end of the first transmission line 20A in the second set ofcoupled lines 20 being a terminated (isolated) port. A second end of thefirst transmission line 20A in the second set of coupled transmissionlines 20 is electrically connected to a second end of the secondtransmission line 10B in the first set of coupled transmission lines 10via an electrical conductor 34. A first end of the second transmissionline 10B in the first set of coupled transmission lines 10 iselectrically connected to a first end of a third transmission line 20Cin the second set of coupled transmission lines 20 via an electricalconductor 54. A second end of the third transmission line 20C in thesecond set of coupled transmission lines 20 is electrically connected toa second end of a fourth transmission line 10D in the first set ofcoupled transmission lines via an electrical conductor 44. A first endof the fourth transmission line 10D in the first set of coupled linesbeing a second output port P2. The first transmission line 20A in thesecond set 20, the second transmission line 10B in the first set 10, thethird transmission line 20C in the second set 20 and the fourthtransmission line 10D in the first set 20 connected electrically to eachother via said electrical conductors 34, 44, 54 are forming a secondspiral shaped electrical conductive path.

The first and third transmission lines 20A and 20C belonging to thesecond set of coupled transmission lines are arranged on the second sideof the dielectric substrate and the second and third transmission lines10B and 10C belonging to the first set of transmission lines arearranged on a first side of said dielectric substrate.

In the spiral shaped electrical conductive paths every second a halfturn of said spiral are belonging to the first set of coupledtransmission lines and between said half turns the transmission linesbelonging to the second set of transmission lines are arranged.

In the embodiment shown in FIG. 1 there are three transposition portions30, 40, 50 of the first and second spiral shaped conductive paths.

In a first transposition portion 30 the electrical conductors 32, 34connecting the second end of the first transmission line 10A in thefirst set of coupled lines 10 to the second end of the secondtransmission line 20B in the second set of coupled lines 20 and thesecond end of the second transmission line 10B in the first set ofcoupled transmission lines 10 to the second end of the firsttransmission line 20A in the second set of coupled transmission lines 20respectively.

In a second transposition portion 40 the electrical conductors 42, 44connecting the second end of the third transmission line 10C in thefirst set of coupled lines 10 to the second end of the fourthtransmission line 20D in the second set of coupled lines 20 and thesecond end of the fourth transmission line 10D in the first set ofcoupled transmission lines 10 to the second end of the thirdtransmission line 20C in the second set of coupled transmission lines 20respectively.

In a third transposition portion 50 the electrical conductors 52, 54connecting the first end of the second transmission line 10B in thefirst set of coupled lines 10 to the first end of the third transmissionline 20C in the second set of coupled lines 20 and the first end of thethird transmission line 10C in the first set of coupled transmissionlines 10 to the first end of the second transmission line 20B in thesecond set of coupled transmission lines 20 respectively.

With reference to FIG. 5, a physical layout of a four port hybrid 100Daccording to the invention is shown. The hybrid 100D comprising a firstset 10 and a second set 20 of coupled transmission lines. Said first setof coupled transmission lines 10 comprising a first transmission line10A, a second transmission line 10B, a third transmission line 10C and afourth transmission line 10D. Said second set of transmission lines 20comprising a first transmission line 20A, a second transmission line20B, a third transmission line 20C and a fourth transmission line 20D.In the present embodiment the transmission lines 10A, 10B, 10c, 10D,20A, 20B, 20C, 20D are C-shaped. The first transmission line 10A, 20A isthe longest one and the second 10B, 20B, third 10C, 20C and fourth 10D,20D are decreasing by gradual stages. Every transmission line 10A, 10B,10C, 10D in the first set 10 is interacting with each other, that meansthey are more or less capacitively coupled to each other, the closer thetransmission lines are to each other the bigger the coupling betweensaid transmission lines. The same applies to every transmission line inthe second set of coupled transmission lines 20.

A first end of the first transmission line 10A in the first set ofcoupled transmission lines 10 being an input port P1. Said input port P1in this physical implementation is a pad electrically connected to theend of the first transmission line 10A. Said pad like the transmissionlines in the hybrid pattern is for example manufactured by printing,sputtering or etching. A second end of said transmission line 10A iselectrically connected to a second end of the second transmission linein the second set of coupled transmission lines via an electricalconductor 32. A first end of the second transmission line 20B in thesecond set of coupled transmission lines 20 is electrically connected toa first end of the third transmission line 10C in the first set ofcoupled transmission lines 10 via an electrical conductor 52. A secondend of the third transmission line in the first set of coupledtransmission lines is electrically connected to a fourth transmissionline in the second set of coupled transmission lines via an electricalconductor 42. A first end of the fourth transmission line in the secondset of coupled transmission lines being a first output port P3 beingformed as a pad and connected to said end of said transmission line. Thefirst transmission line 10A in the first set 10, the second transmissionline 20B in the second set 20, the third transmission line 10C in thefirst set 10 and the fourth transmission line 201 in the second set 20coupled electrically to each other via said electrical conductors 32,42, 52 are forming a first spiral shaped electrical conductive path.

A first end of the first transmission line 20A in the second set ofcoupled lines 20 being a port connectable to ground. A second end of thefirst transmission line 20A in the second set of coupled transmissionlines 20 is electrically connected to a second end of the secondtransmission line 10B in the first set of coupled transmission lines 10via an electrical conductor 34. A first end of the second transmissionline 10B in the first set of coupled transmission lines 10 iselectrically connected to a first end of a third transmission line 20Cin the second set of coupled transmission lines 20 via an electricalconductor 54. A second end of the third transmission line 20C in thesecond set of coupled Ad transmission lines 20 is electrically connectedto a second end of a fourth transmission line 10D in the first set ofcoupled transmission lines via an electrical conductor 44. A first endof the fourth transmission line 10D in the first set of coupled linesbeing a second output port P2 being like the first output port formedlike a pad and connected to the end of said transmission line. The firsttransmission line 20A in the second set 20, the second transmission line10B in the first set 10, the third transmission line 20C in the secondset 20 and the fourth transmission line 10D in the first set 20 coupledelectrically to each other via said electrical conductors 34, 44, 54 areforming a second spiral shaped electrical conductive path.

In the spiral shaped electrical conductive paths every second half turnof said spiral are belonging to the first set of coupled transmissionlines and between said half turns the transmission lines belonging tothe second set of transmission lines are arranged.

In the embodiment shown in FIG. 5 there are three electrically isolatedtransposition portions 30, 40, 50 of the first and second spiral shapedconductive paths. In a first transposition portion 30 the electricalconductors 32, 34 connecting the second end of the first transmissionline 10A in the first set of coupled lines 10 to the second end of thesecond transmission line 20B in the second set of coupled lines 20 andthe second end of the second transmission line 10B in the first set ofcoupled transmission lines 10 to the second end of the firsttransmission line 20A in the second set of coupled transmission lines 20respectively. In a second transposition portion 40 the electricalconductors 42, 44 connecting the second end of the third transmissionline 10C in the first set of coupled lines 10 to the second end of thefourth transmission line 20D in the second set of coupled lines 20 andthe second end of the fourth transmission line 10D in the first set ofcoupled transmission lines 10 to the second end of the thirdtransmission line 20C in the second set of coupled transmission lines 20respectively. In a third transposition portion 50 the electricalconductors 52, 54 connecting the first end of the second transmissionline 10B in the first set of coupled lines 10 to the first end of thethird transmission line 20C in the second set of coupled lines 20 andthe first end of the third transmission line 10C in the first set ofcoupled transmission lines 10 to the first end of the secondtransmission line 20B in the second set of coupled transmission lines 20respectively.

In every transposition portion in FIG. 5 one of the electricalconductors connecting two transmission lines from different set ofcoupled transmission lines is printed like the rest of the pattern ofthe hybrid. The other electrical conductors, isolated from the printedones are for example bonding wires between the two transmission lines.

Capacitors 51, 53, 57, 43, 41, 33, 31 are arranged like a meander shapedpattern at both ends of the second, third and fourth transmission lines.The meander shaped pattern at the ends of the transmission lines in thefirst set of coupled transmission lines are adapted to the meandershaped pattern at the ends of the transmission lines in the second setof coupled transmission lines.

In the embodiment in FIG. 5 a capacitor 57 is arranged between the firstand second output port. Said capacitor will also contribute to theequalization of the different modes propagating across the hybrid.

With reference to FIG. 6, a schematic view of a fifth embodiment of afour port hybrid 100F according to the invention is shown. Differentlayers in the hybrid are separated in the figure for the purpose ofclarity, in reality said layers are closely arranged to each other. Thehybrid 100F comprising a first set 10 and a second set 20 of coupledtransmission lines. Said first set of coupled transmission lines 10comprising a first transmission line 10A, a second transmission line 10Band a third transmission line 10C. Said second set of transmission lines20 comprising a first transmission line 20A, a second transmission line20B and a third transmission line. In the present embodiment thetransmission lines 10A, 10B, 10C, 20A, 20B, 20C are C-shaped. The firsttransmission lines 10A, 20A are arranged on a first layer X in adielectric substrate, the second transmission lines 10B, 20B arearranged on a second layer Y in the dielectric substrate and the thirdtransmission lines 10C, 20C are arranged on a third layer Z in thedielectric substrate. The different layers X, Y, Z in the substrate areelectrically isolated from each other. Every transmission line 10A, 10B,10C in the first set 10 is interacting with each other, that means theyare more or less capacitively coupled to each other, the closer thetransmission lines are to each other the bigger the coupling betweensaid transmission lines. The same applies to every transmission line inthe second set of coupled transmission lines 20. The shape of thetransmission lines in the first set 10 and the second set could asindicated in FIG. 6 be equal. However the length and shape could bedifferent for the different transmission lines 10A, 10B, 10C, 20A, 20B,20C.

A first end of the first transmission line 10A in the first set ofcoupled transmission lines 10 being an input port P1. A second end ofsaid transmission line 10A is electrically connected to a second side ofthe second transmission line 20B in the second set of coupledtransmission lines 20 via an electrical conductor 32. A first side ofthe second transmission line 20B in the second set of coupledtransmission lines 20 is electrically connected to a first side of thethird transmission line 10C in the first set of coupled transmissionlines 10 via an electrical conductor 44. A second side of the thirdtransmission line 10C in the first set of coupled transmission lines 10being a first output port P2. The first transmission line 10A in thefirst set 10, the second transmission line 20B in the second set 20 andthe third transmission line 10C in the first set 10 are coupledelectrically to each other via said electrical conductors 32, 44 andforming a first spiral (helix) shaped electrical conductive path.

A first end of the first transmission line 20A in the second set ofcoupled lines 20 being a port P4 connectable to ground. A second end ofthe first transmission line 20A in the second set of coupledtransmission lines 20 is electrically connected to a second end of thesecond transmission line 10B in the first set of coupled transmissionlines 10 via an electrical conductor 34. A first end of the secondtransmission line 10B in the first set of coupled transmission lines 10is electrically connected to a first end of a third transmission line20C in the second set of coupled transmission lines 20 via an electricalconductor 42. A second end of the third transmission line 20c in thesecond set of coupled transmission lines 20 being a second output portP3. The first transmission line 20A in the second set 20, the secondtransmission line 10B in the first set 10 and the third transmissionline 20C in the second set 20 are coupled electrically to each other viasaid electrical conductors 34, 42 and forming a second spiral (helix)shaped electrical conductive path.

In the spiral shaped electrical conductive paths every second half turnof said spiral are belonging to the first set of coupled transmissionlines and between said half turns the transmission lines belonging tothe second set of transmission lines are arranged. In this embodimentevery second half turn of the spirals are belonging to a different layercompared to the previous half turn if any such half turn is existing inthe structure and the next coming half turn if any such half turn in thestructure is existing.

In the embodiment shown in FIG. 6 there are two electrically isolatedtransposition portions 30, 40 of the first and second spiral shapedconductive paths. Said electrically isolated transposition portions 30,40 can be looked upon as four port cross connectors. In a firsttransposition portion 30 the electrical conductors 32, 34 connecting thesecond end of the first transmission line 10A in the first set ofcoupled lines 10 to the second end of the second transmission line 20Bin the second set of coupled lines 20 and the second end of the secondtransmission line 10B in the first set of coupled transmission lines 10to the second end of the first transmission line 20A in the second setof coupled transmission lines 20 respectively.

In a second transposition portion 40 the electrical conductors 42, 44connecting the first end of the third transmission line 10C in the firstset of coupled lines 10 to the first end of the second transmission line20B in the second set of coupled lines 20 and the first end of thesecond transmission line 10B in the first set of coupled transmissionlines 10 to the first end of the third transmission line 20C in thesecond set of coupled transmission lines 20 respectively.

The hybrid with N coupled transmission lines will have (N−1)transposition portions.

The hybrid can have a first capacitor coupled between ground and theinput port.

The transmission lines can be of any shape for example straight lines ormeander shaped instead of the above mentioned C shaped transmissionlines

The invention being thus described, it will be obvious that the same maybe varied in a plurality of ways. Such variations are not to be regardedas a departure from the scope of the invention. All such modificationsas would be obvious to one skilled in the art are intended to beincluded within the cope of the appended claims.

What is claimed is:
 1. A four port hybrid comprising a first set (10) ofN coupled transmission lines (10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H,10I) and a second set (20) of N coupled transmission lines (20A, 20B,20C, 20D, 20E, 20F, 20G, 20H, 20I) where N≧3, said coupled transmissionlines in said first set (10) are electrically connected to said coupledtransmission lines in said second set (20) to form a first spiral shapedelectrical conductive path, a second spiral shaped electrical conductivepath and N−1 electrically isolated transposition portions (30, 40, 50,60, 70, 80, 90, 110) of said first and second spiral shaped electricalconductive paths, where a first end of the first spiral being an inputport (P1), a first end of the second spiral being a terminated port(P4), a second end of the first spiral being a first output port (P3), asecond end of the second spiral being a second output port (P2).
 2. Afour port hybrid according to claim 1, characterised in that said firstset (10) of N coupled transmission lines is a mirror image of saidsecond set (20) of N coupled lines.
 3. A four port hybrid according toclaim 1, characterised in that said transmission lines in said first andsecond set (10) of coupled transmission lines are C-shaped.
 4. A fourport hybrid according to claim 1, characterised in that the first (10)and second (20) set of transmission lines and the electrical connectionbetween them are arranged on one side of a dielectric substrate.
 5. Afour port hybrid according to claim 1, characterised in that at leastone of the transmission lines is arranged on a first side of thedielectric substrate and the rest of the transmission lines are arrangedon the second side of said dielectric substrate.
 6. A four port hybridaccording to claim 1, characterised in that a first transmission line(10A, 20A) in the first and second set (10, 20) are arranged on a firstlayer (X) in the dielectric substrate, a second transmission line (103,20B) in the first and second set (10, 20) are arranged on a second layer(Y) in the dielectric substrate and a N:th transmission line in thefirst and second set (10, 20) are arranged on a N:th layer in thedielectric substrate, where said layers are electrically isolated fromeach other.
 7. A four port hybrid according to claim 1, characterised inthat at least one isolated transposition portion (30, 40, 50, 60, 70,80, 90 110) having two capacitors (51, 53, 41, 43, 31, 33) beingarranged between the ends of the transmission lines in such a manner toform further RF connections, which capacitors will equalise phasevelocities for all modes propagating in the hybrid.
 8. A four porthybrid according to claim 1, characterised in that a capacitor (57) isarranged between the first output port and the second output port (P2,P3).